You can use a logical conjunction to combine two or more
Boolean expressions. To do this, use the where statement to create
the expression as you see fit. Here is an expression that uses a logical
disjunction (&&) operation:

To negate a conjunction, precede it with a ! operator.
Remember that a conjunction is made of two parts. Therefore, if you want to
negate only the first part, precede it with !. If you want to negate the
whole conjunction, put the conjunction in parentheses but precede it with !
(outside the parentheses).

Disjunction

When creating a LINQ statement, you can use a logical
disjunction. You do this with the C#'s OR operator, which is ||.